The present invention relates, in general, to a servo mechanism for a seat part, especially of a chair, like in an office or work chair
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Published U.S. Pat. Appl. No. 2006/0244294 discloses a chair, especially an office or work chair, having a seat part which can be moved on a support frame in longitudinal direction in synchronism to a back rest part which can be reclined from a normal position to several tilted positions. The seat part may also be optionally guided for tilting relative to the support frame. A return device is connected to the free end of a supporting arm of the support frame and connected with the seat part, for transfer of return loads onto the seat part and/or the back rest part. The return device is implemented in the form of a pneumatic spring assembly. Such a pneumatic spring assembly requires however much installation space and thus is relatively expensive. In addition, problems are encountered to produce a counterforce which is as even as possible during movement of the seat part and the back rest part.
It would therefore be desirable and advantageous to address this problem and to obviate other prior art shortcomings.